Because small, precision high, high sensitivity and definition higher advantage with low price of having size of SAW sensor, so has produced SAW gas sensor composed of surface acoustic wave device, sensitive membrane and relevant detection circuit. The sensitive membrane is in the course of absorbing gaseously, the stress that the gas examined causes is acted on the medium in the surface
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acoustic wave transmission path, make its characteristic of dynamics change, and then change the resonant frequency of the surface acoustic wave device. This variation happens in the detection circuit test related to it, thus the gaseous relation property of awaiting measuring, and technical indicators such as precision and accuracy grade of the whole sensor of direct influence of relevant characteristic of the detection circuit, etc. So, the design of the circuit is an essential link in SAW gas sensor. Surface acoustic wave SAW The Shaker uses surface acoustic wave resonator or delay cable as the frequency stabilization component to form. The surface acoustic wave device usually adopts the stable single crystal quartz material of characteristic to be made, the frequency outputted is very steady. The fundamental operating frequency of the sound surface wave oscillator is high, the operating range is very high to 2000MH z, body of low frequency acoustic wave oscillator different relatively with traditional adoption, have the intersection of weight and light, the intersection of volume and little, the intersection of power consumption and little, low cost, the intersection of reliability and the intersection of increase, etc. and advantage. The sound surface wave oscillator is regarded as the response element of the surface acoustic wave sensor, definition, stability and testing the precision of its direct influence sensor...
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